Method of treating the outer surface of softboard products



Dec. 12, 1967 E. R. WENGENROTH, JR 3,357,847

METHOD OF TREATING THE OUTER SURFACE OF SOFTBOABD PRODUCTS Filed Dec. 13, 1963 5 Sheets-Sheet 1 TRIMMING TILING SANDPAPER ROLLS PAINTING DRYING FORMING FISSURES a PIN HOLES FIG. 2.

TRIMMING u'x 4) BOARD FORMING 1967 E. R. WENGENROTH, JR 3,357,347

METHOD OF TREATING THE OUTER SURFACE OF SOFTBOARD PRODUCTS 3 Sheets-Sheet 2 Filed Dec. 15, 1965 W ..v v E 7 W AHA, W4" WA d fiw a W% 1 MW; u I

1967 E. R. WENGENROTH, JR 3,357,347

METHOD OF TREATING THE QUTER SURFACE OF SOFTBOARD PRODUCTS Filed Dec. 13, 1963 5 Sheets-Sheet 5 FIG. 5.

FIG. 4.

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FIG. 6.

United States Patent 3,357,847 METHUD 0F TREATING THE OUTER SURFACE OF 0FTBOARD PRODUCTS Edgar R. Wengenroth, Jr., Wayne, N.J., assignor to The Flintkote Company, New York, N .Y., a corporation of Massachusetts Filed Dec. 13, 1963, Ser. No. 330,465

4 Claims. (Cl. 117-8) This invention relates generally to wall and ceiling surfacing products made of softboarc, and particularly to improvements in the surface texture, light reflectivity, appearance and sound absorption of such products.

As used herein, softboar is intended to refer to manufactured decorative boards that sustain their shapes and that have a density, at least adjacent the exposed surface, such that they may be permanently deformed or indented relatively easily. Such products are well known in the building materials industry and generally are produced by forming a slurry of fibers and a suitable binder which is then dried and formed and cut to produce a board of the desired thickness, size and shape. Various types of fibers have been commonly used, such as cellulose fibers, mineral wool fibers, glass wool fibers and asbestos fibers. It should be understood, however, that the instant invention has utility on any softboard material having the requisite characteristics with respect to density and use, whether fibers are included or not. This invention has proven of particular value in improving the uroperties of products composed of cellulosic fibers and a starch binder, commonly known in the trade as insulation board.

Ithas long been a practice to form holes or fissures in softboard material to provide a pleasing, non-uniform surface appearance and to improve the sound absorbing properties of the material. Pin holes in softboard material have been produced many ways in the past, though a particularly satisfactory method has comprised simply puncturing the material to the desired depth with tapered pins. Elongated fissures are most commonly formed in insulation board by either embossing or by localized blasting with a pulverulent abrasive. For example, in Brown et al. Patent No. 3,013,937, the pin holes are formed by pins carried by a rotating cylinder, and the fissures are formed by rotating cylinders which carry suitably shaped dies. In Proudfoot Patent No. 2,791,289, the pin holes are formed by pins or tines carried by a reciprocable press and the fissures are produced by spraying abrassive particles through a templet onto the insulation board.

It is the principal object of this invention to improve the appearance, surface texture and sound absorbing properties of softboard material, particularly of the felted, fibrous type discussed above. A further object is to provide means affording a more simple, economical and flexible method of improving the surface texture of softboard material.

This invention resides in a novel treatment of the softboard material, following painting or other similar processing, whereby the surface of the softboard material is characterized by shallow depressions which provides a pleasing surface texture, and which when used in combination with pin holes and fissures in the surface help to provide a more gradual change in the light reflectivity of the material. Although softboard having such depressions in combination with both fissures and pin holes produces the most desirable appearance, the surface treatment in accordance with this invention may be utilized successfully with either the pin holes or the fissures alone. This treatment also serves to improve the surface texture of smooth-surfaced, painted softboard without requiring other more expensive procedures.

As described more fully hereafter, the treatment of softboard to produce the desirable surface texture according to this invention comprises subjecting the face of the softboard to pressure against a shallow embossing surface which most satisfactorily can be provided by very coarse ordinary abrasive paper. Following the normal steps of producing the softboard, and treating the surface by fissuring, puncturing and/or painting, where desired, the softboard is delivered beneath a pressure roll which has the coarse grit abrasive paper affixed to its surface. Thus, each granule of abrasive constitutes an embossing element for producing a shallow depression or indentation without appreciably breaking or piercing through the softboard surface. Softboard material treated in this manner presents 'a more pleasing appearance particularly when used in conjunction with fissures and pin holes. The fissures, which have irregular shapes and varying depths, present a gradual change in light reflectivity of the surface while the pin holes represent points of sharply defined contrast in light reflectivity with the unbroken softboard surface. The shallow depressions or indentations thus serve to provide an overall relief or transition effect in light reflectivity which gives the softboard surface a softer, textured appearance. Also, tests have revealed that the shallow depressions are responsible for an improvement in the sound absorbing qualities of the softboard material.

Another significant advantage of utilizing a common type of coarse sandpaper is the substantially lower cost as compared to conventional embossing dies, thereby permitting greater design flexibility in avoiding pattern repetition and in modifying the textured effects produced.

Further objects, advantages and details of the invention will be understood from the following description when read with reference to the accompanying drawings in which:

FIG. 1 is a block diagram of a complete process of softboard production including the novel additional step in accordance with this invention;

FIG. 2 is a perspective illustration of the rolls between which the softboard material passes for treatment according to this invention;

FIG. 3 is an enlarged partial end view, cross section, of the rolls shown in FIG. 2;

FIG. 4 is the face view of a single softboard tile in which only fissures and pin holes have been formed;

FIG. 5 is the face view of a softboard tile which has been subjected to pressure from a roll having an open, coarse grit surface, whereby shallow depressions are formed in addition to the fissures and pin holes;

FIG. 6' is-a partial cross-sectional view of the softboard tile shown in FIG. 4; and

FIG. 7 is a partial cross-sectional view of the softboard tileshown in FIG. 5.

' The first basic operation in producing softboard material is generally designated as the Board Forming step in FIGURE 1. This operation differs for various types of softboard but is so well known in the art with respect to each type as to require no detailed description. Briefly, in the case of softboard of the type known as insulation board, this involves the pressing and drying of a slurry containing cellulosic fibers, such as wood fibers, and a suitable starch binder. Although the fibrous stock can be derived from any of various sources, the present inpartially in vention has particular merit in its application to felted cellulosic fibers. (To those skilled in the art it will be recognized that in this area there is involved a desire to simulate the fissured, textured appearance of mineral wool tile.) The density of conventional soft'boards are generally in the range of 14 to 18 pounds per cubic foot and the thickness typically is one-half inch, though other thicknesses are commonly used for certain applications. Following the Board Forming step, there is generally a step designated as rimming (FIG. 1) in which the continuous board is preliminarily cut into pieces of a desired size, such as one-by-four feet.

As previously indicated, this invention is particularly useful to soften the surface appearance of softboard material that already has fissures and pin holes formed in its surface. Thus, in FIG. 1 there is represented the step (or steps) of Forming Fissures and Pin Holes. However, as indicated above, either or both of these steps may be omitted, thereby increasing the flexibility of design on the same equipment. If fissures are to be produced, this can be effected by either of the techniques disclosed respectively in the aforementioned Brown Patent 3,013,937 (embossing) and Broudfoot Patent 2,791,- 289 (sandblasting). The pin holes can be produced by either of the simple techniques also disclosed in these patents or in any other conventional manner. The softboard is then sprayed with paint, preferably a waterb-ased acrylic resin emulsion, and the paint coating is dried, as represented at Painting and Drying in FIG. 1. Normally, i.e., in the present manufacture of insulation board ceiling tiles, the pieces of softboard proceed next to the operation represented at Trimming and Tiling in FIG. 1, which consists of cutting the board into tiles of the desired size, usually to form an outer surface one foot square, and of shaping the tile edges in the desired manner to permit ready installation in any of various well known ways. However, in accordance with this invention there is interposed (following the painting and drying and prior to trimming and tiling) the additional Sandpaper Rolls step generally designated at 10 in FIG. 1.

Referring to FIG. 2, the apparatus for performing the Sandpaper Rolls step includes a pair of slightly spaced, parallel cylindrical press rolls 12 and 16, the roll 16 being substantially smooth-surfaced and the roll 12 having a sandpaper surface 14. The spacing between the surfaces of rolls 12 and 16 is adjusted to be about the same or slightly less than the thickness (generally about /z-inch) of the softboard tile T which is fed between the nip of the rolls. Preferably, both the rolls 12 and 16 are driven in synchronisrn at the same circumferential speed (by conventional means, not shown) although either or both rolls may act as idlers and not be driven. The axial length of rolls 12 and 16 should be the same or greater than the width (about 48 to 50 inches) of the tile T. In order to properly carry out the present invention, the rotational speed of roll 12 should approximate the linear speed of the tile T and the direction of rotation of roll 12 at the nip between the rolls should be the same as the direction of travel of the tile T.

Practically the entire effect of the present invention is attributable to the surface properties of what has been referred to, for Want of a better term as the sandpaper surface 14 adhered to the roll 12. Referring to FIG. 3, a heavy paper backing is identified at 18. Backing 18 has a synthetic resinous coating 22 in which are embedded many crystal-type granules or particles 20. A significant advantage of this invention is that the surface 14 may be readily supplied by standard trade in the form of open, coarse grit abrasive paper. The term sandpaper has been used herein in its popular sense which is inclusive of industrial abrasive papers that embody varying types of materials as grit or cutting particles. Quartz crystals, for example, are used on some papers, particularly for wood surfacing uses, although silicon carbide has become a principal all-purpose abrasive. In actual commercial production of ceiling tile made from cellulosic insulation board material in accordance with this invention, a silicon carbide type paper designated as #4 /212 grit type F, Grit-Lok, Resinite, Open Coat (manufactured by Minnesota Mining and Manufacturing Company) has been used with complete satisfaction. For this type of material it is preferable to use from #4 to #4V2 open grit papers, or higher, however the further properties and ranges of particle sizes for use in this invention will be discussed more fully hereafter. For the present, it may be noted that in #4 /2 grit open grit paper, the irregularly shaped jagged crystalline particles 20 have their largest dimension ranging typically from about A -inch up to about /s-inch, and their dispersement can be estimated as ranging from about 30 to about particles per square inch.

As illustrated, the softboard tiles T are delivered at the nip of rolls 12 and 16 following the formation of the fissures and the pin holes. In FIGS. 3 to 7 these pin holes will be identified by the reference numeral 24. The fissures 26, whether produced by sandblasting or other techniques, are elongate in nature and typically measure from around /2 to A-inch in length, although they may extend to several inches in length. They generally have a depth of less than one-half of the thickness of the tile T although they have sufficient depth to break or disrupt the intertwined fibrous mat which forms the body of the tile T. The pin holes 24 usually measure Mag-limb or less in diameter, and generally extend to a depth greater than one-half the thickness of the tile T, penetrating through its entire thickness if desired. A ceiling tile made of insulation board and having only fissures 26 and pin holes 24, appears somewhat as pictured in FIG. 4.

As the softboard passes between rolls 12 and 16, the granules or particles 20 are pressed into the painted surface 30, thereby producing indentations or depressions 28 which resemble pockmarks. In FIG. 5 the size and distribution of depressions 28 are necessarily somewhat exaggerated, for it will be evident that these depressions will coincide with the distribution and size of particles 20. The jagged particles 20 do not normally break through the surface 30, but merely displace the fibers sufficiently to produce depressions in the surface resulting in very soft shadow effects in the glazed, unbroken areas of the surface and thereby serve as a transition in surface texture from the fissures to the pin holes. This displacing or compressing action is to be contrasted with the very definite breaking of the fibrous body of the softboard which is inherent in the production of a fissure 26 or a pin hole 24, both of which penetrate deeply into the body of tile T. In the specific example given herein, the depressions 28 range from 15 to 47 mils in depth.

Although the easiest and most versatile procedure for producing the depressions or pockmarks 28 contemplates the use of conventional open-grit, coarse grade sandpaper, other conventional procedures may be used to practice this invention, should they be desirable for certain purposes. It should be recognized that even though commercial sandpaper is preferably used to produce the effect desired, no sanding (as this term is normally understood) of the surface of the softboard is produced. The effect desired is produced rather by a pressing action, which may be considered as a type of embossing. Thus, where a sandpaper roll is used to produce this effect, as illustrated herein, it is important that the direction of travel of the roll surface at the point of engagement with the softboard tile be the same as the direction of travel of the tile itself and that the rotational speed of the roll surface at this point be approximately the same as the linear speed of the tile.

A particularly significant advantage of this invention is the relative simplicity and economy of solving the problem of noticeable recurring patterns in tile. Whereas the production of any type of surface effect by embossing dies involves a sufiiciently high cost as to prohibit much variation in patterns, the negligibly low cost of industrial abrasive papers practically eliminates cost considerations in any decision to modify patterns. Complete flexibility of pattern and design is, therefore, a readily attainable attribute of this invention.

Reference has been made to the preference for #4 to #4 /z grit open abrasive papers. Coarseness grades over #4 /2 or less than #4, say down to around #3 to #3 /2, can be used where the surface brittleness, density and other properties of the particular type of softboard material used are such as to indicate the desirability of utilizing such grades. Particle distribution of less than 30 per square inch may be used, where less texturing is desired, however it is preferred that particle distribution should not exceed 75 per square inch.

Although it is not claimed that the addition of depressions 28 alone effects any drastic improvement in sound transmission loss, actual tests have revealed an improvement of approximately 5%, which improvement can be significant for certain purposes. However, it will be recognized, that this is an adjunct to the principal advantages of improved surface texture and overall appearance.

It will be understood that various departures from the specifically disclosed embodiments of the invention may be made without departing from the scope thereof as defined by the following claims.

What is claimed is:

1. A method of treating the relatively smooth outer surface of a softboard material comprising the steps of forming a plurality of elongated fissures and substantially circular holes which break the surface and extend into the body of said softboard material, thereafter painting the unbroken portion of said surface, and then forming a plurality of relatively shallow indentations in said unbroken portion of said surface, said indentations having a depth such as to create visible variations in the light reflectivity off of said unbroken portion of said surface without destroying the paint film thereover.

2. In the method according to claim 1, wherein said 5 at the point of mutual contact.

3. In the method according to claim 2, wherein said particles are provided by a conventional open, coarse grift abrasive type paper and wherein said paper is mounted on a rotatable pressure roll.

10 4. In the method according to claim 3, wherein said jagged particles range in approximate size from to /s inch and are distributed in the range of 30 to 50 particles per square inch.

References Cited UNITED STATES PATENTS 2,681,865 6/1954 Heine 117-8 3,086,878 4/1963 Lauring 117-8 2,529,210 11/1950 Butler 83-11 3,120,777 2/1964 Genin 83-11 2,459,121 1/1949 Willey et al 181-33 3,013,626 12/1961 Brown et al. 181-33 1,945,003 1/1934 Smolak et al. 181-33.11 2,791,289 5/1957 Proudfoot et al. 181-33.11

3,077,945 2/1963 Thomas et a1. 117-8 3,012,285 12/1961 Marcus et a1 117-8 3,086,878 4/1963 Lauring 117-8 3,206,346 9/1965 Nvorivaara 264-284 ALFRED L. LEAVITT, Primary Examiner.

LEO SMILOW, Examiner. 

1. A METHOD OF TREATING THE RELATIVELY SMOOTH OUTER SURFACE OF A SOFTBOARD MATERIAL COMPRISING THE STEPS OF FORMING A PLURALITY OF ELONGATED FISSURES AND SUBSTANTIALLY CIRCULAR HOLES WHICH BREAK THE SURFACE AND EXTEND INTO THE BODY OF SAID SOFTBOARD MATERIAL, THEREAFTER PAINTING THE UNBROKEN PORTION OF SAID SURFACE, AND THEN FORMING A PLURITY OF RELATIVELY SHALLOW INDENTATIONS IN SAID UNBROKEN PORTION OF SAID SURFACE, SAID INDENTATIONS HAVING A DEPTH SUCH AS TO CREATE VISIBLE VARIATIONS IN THE LIGHT REFLECTIVITY OFF OF SAID UNBROKEN PORTION OF SAID SURFACE WITHOUT DESTROYING THE PAINT FILM THEREOVER. 